Mustelids (ferrets, stoats and weasels) were first introduced in the 1880s to control New Zealand’s growing rabbit plagues, but had limited impact on rabbit populations.
They have become a major predator of native birds and in particular native flightless birds such as the kiwi and takahe have suffered heavy predation. Recently ferrets have also been discovered to be carriers of Bovine Tb.
Mustelids are a major threat to poultry farms, especially ‘free-range’ farms, and will also target pets such as guinea pigs or rabbits. Ferrets, stoats and weasels live in home ranges, which vary in size up to 200ha. Males inhabit larger areas than females.
Most young are born during spring or early summer and the size of litters is dependent upon the abundance of food. In Hawke’s Bay ferrets, stoats and weasels are classed as site-specific animal pests.
For details of this requirement, please refer to the Regional Pest Management strategy or contact Biosecurity Animal Pest Officers at Hawke’s Bay Regional CouncilMustelid Species in New Zealand:
Ferrets (Mustela furo)
Ferrets have a creamy-yellow undercoat, with long black guard hairs, which give a generally dark appearance. Legs and tail appear darker than the body. The lighter facial region has a dark mask around the eyes and across the nose. Male ferrets grow up to 440 mm and females up to 370 mm in length.
Physical ability:
Smell and hearing are ferrets’ main senses. Their eyesight is poor by day, but better at night. Ferrets, compared to stoats, are poor swimmers and climbers.
Diet:
Ferrets eat birds, eggs, rabbits, possums, rodents, hedgehogs, frogs, eels, insects and carrion.
Preferred habitat:
Ferrets are relatively common throughout farmland and along forest margins, particularly in areas containing high rabbit numbers.
Stoats (Mustela erminea):
Stoats have long thin bodies with smooth pointed heads. Ears are short and rounded. Their fur is dark brown with creamy white under-parts. Stoats have relatively long tails with a bushy black tip. They are smaller than ferrets; males grow up to 300 mm and females up to 250 mm long.
Physical ability:
Stoats have sharp claws and are very nimble tree climbers. They are strong swimmers and islands within 1.5 km of the mainland are vulnerable to stoat invasion.
Diet:
Stoats eat birds, eggs, rodents, rabbits, possums, lizards, freshwater crayfish, insects (wetas), and occasionally carrion or household rubbish.
Preferred habitat:
Stoats can be found anywhere from beaches to the high country, in native or exotic forest scrub, dunes, tussock and on farmland.
Weasels (Mustela nivalis vulgari):
Weasels are the smallest mustelid in New Zealand, with males growing to about 200 mm. Their fur is brown with white underparts often broken by brown spots. Their tails are short, brown and tapering.
Physical ability:
Weasels run, swim and climb as well as stoats, but have a shorter stride and cover less distance.
Diet:
Weasels commonly feed on mice, small birds and eggs, lizards and wetas. They will occasionally tackle larger prey such as rabbits.
Preferred habitat:
Weasels are the rarest of the mustelids found in New Zealand. They prefer modified habitats such as farmland, forest margins, and scrub, and can occasionally be found in suburban gardens.
Field sign:
Mustelid scats (droppings) are long and thin, often with a characteristic tapering twist at each end. They are filled with fur, feathers and bone fragments, and are hard and black when dry. Mustelids secrete onto their scats a thick, oily powerful smelling yellow fluid called musk.
The scats are often placed in conspicuous positions, such as in the middle of a track, as a sign to other mustelids in the area. Another mustelid characteristic is that they eat the flesh from the neck and head area of their prey.
Information Sourced From:
